1. Field of the Invention
The present invention relates to a centrifugal pump for circulating a liquid, and more particularly to a pump operating by vessel oscillation, suitable for a blood circulation device such as an artificial heart or an assisted circulation device or the like.
2. Discussion of the Background
In the past, pumps of this kind have been known which are designed, for example, as shown in FIGS. 11 and 12. More specifically, they comprise a vessel (a), an outlet opening (b) provided in a tangential direction of an outer periphery at the lower part of the vessel (a), and an inlet (c) in the central portion at the upper part of the vessel (a). A sealed rotary shaft (d) is provided in the central portion at the lower part of the vessel (a), the rotary shaft (d) being extended within the vessel (a). An umbrella-like rotor (e) is secured to the end of the shaft within the vessel, the rotor (e) and shaft (d) being rotated by a drive device (not shown) from the bottom of the shaft.
In the pump constructed as described above, the liquid flowing into the vessel (a) from the upper inlet (c) is rotated by the rotation of the rotor (e) and formed into a centrifugal flow which flows out of the outlet opening (b).
Accordingly, in the case where the above-described pump is used for the artificial heart or the like, the rotor rotates within the vessel and therefore various germs, air, foreign matter or the like are possibly mixed with the blood via the bearing, which might cause hemolysis (destruction of red blood cells or thrombus (condensation of blood). In addition, since the bearing for rotating the rotor is provided on the vessel, the low durability of the bearing portion, particularly a seal of the bearing has disadvantages.